Not Applicable.
Not Applicable.
This invention relates to support cushions, and in particular to a support cushion that includes a mechanical support system imbedded in foam cushioning material. The mechanical support cushion conforms to a user""s body and maintains substantially uniform pressure distribution within each of a plurality of sections of the cushion. The invention as described herein relates to seat cushions used on chairs, and in particular on seats of wheelchairs. However, it will be appreciated that the support cushion can be readily adapted for use in any situation where it is desired to exert substantially uniform or balance pressures against a body resting thereon. For example, the support system can be used in beds, chairs back supports and the like.
In general, wheelchairs include a seat and backrest that are constructed from flexible material that easily folds when the wheelchair is collapsed. However, the flexible material of the seat and backrest does not provide optimum support or comfort for the occupant. Foam and air filled seat cushions and contoured universal backrests have been developed to provide improved support for individuals requiring special support, such as paraplegics or those having spinal deformities or muscular atrophy, but these seat cushions and backrests are difficult to adjust to accommodate specific needs and proportions of individual users and do not encourage proper control of body position. Users often over use their back muscles in efforts to maintain proper posture. Furthermore, wheelchair users and those confined to beds often become oversensitive to pressures against their skin and bodies so that it is desirable to develop a support cushion that exerts low pressures against a user""s body and skin.
Support cushions have been developed that provide low pressures on a user""s body. For example, U.S. Pat. No. 3,790,150, issued Feb. 5, 1974 to Lippert; U.S. Pat. No. 4,033,567, issued Jul. 5, 1977 to Lipfert; U.S. Pat. No. 4,283,864, issued Aug. 18, 1981 to Lipfert; and U.S. Pat. No. 4,484,778, issued Nov. 27, 1984 to Cousins et al., disclose various mechanical support systems that conform to the shape of the user""s body and distribute pressure over user""s body. However, such support cushions do not provide the necessary postural control and stability for persons such as active paraplegics and active wheelchair users.
Accordingly, it is desirable to develop a support cushion that not only conforms to the shape of the user""s body, but also provides stabilizing forces that allow for postural control. Such a support cushion should provide a stable platform to permit improved control of body position and posture without overusing back muscles. Furthermore, such a support cushion must be durable and able to withstand extensive use for extended periods of time.
Accordingly, it is an object of the present invention to provide a support cushion and method for making the same that conforms to the shape of the user""s body, distributes support pressure and provides a stable support surface for a user.
These and other objects will become apparent to those skilled in the art in light of the following disclosure and accompanying drawings.
In accordance with the invention, generally stated, a support cushion is provided that includes an outer foam shell having a cavity formed therein; foam filling disposed in the cavity of the outer shell; and a mechanical support structure disposed in the cavity and imbedded in the foam filing that distributes pressure exerted on the cushion by a user. The density of the foam shell preferably is greater than the density of the foam filing. In the preferred embodiment, the foam filing is a low density soft urethane foam.
Another aspect of this invention includes a method for making a support cushion, including the steps of: placing a preformed foam shell having a top panel and sidewalls extending downwardly therefrom in a form having dimensions slightly greater than the peripheral dimensions of the top panel; placing a mechanical support structure on the top panel of the foam shell in a cavity defined by the top panel and sidewalls; pouring a foam filing mixture in the cavity of the outer shell so that the mechanical support structure is imbedded in the foam filing after the foam filing cures; placing a bottom panel over the mechanical support before the foam filing cures; and removing the cushion from the form after the foam filing cures.
Other objects and features will be apparent and in part pointed out hereinafter.